VANE PUMP

Abstract

A vane pump includes a rotor; a plurality of slits that are formed in the rotor, the plurality of vanes being respectively inserted into the plurality of slits in a slidable manner; a cam ring that has a cam face on which tip-ends of the vanes slide by the rotation of the rotor; and pump chambers that are defined by the rotor, the cam ring, and an adjacent pair of the vanes. The plurality of vanes have a plurality of first vanes that are formed by applying a DLC coating on a base material and second vanes that are formed such that the base material is exposed, the first vanes being respectively inserted into at least two adjacent slits of the plurality of slits.

Description

TECHNICAL FIELD

The present invention relates to a vane pump.

BACKGROUND ART

JP1999-230057A discloses a vane pump including a rotor that is accommodated in a housing and rotationally driven, vanes that move in a sliding manner in slits in the rotor, and a cam ring that is arranged at the outer side of the vanes and forms pump chambers with the rotor, the vanes, and so forth.

SUMMARY OF INVENTION

Because working oil has high viscosity and high viscous resistance in a low-temperature situation, in the vane pump in the low-temperature situation, the vanes are prevented from sliding due to the viscous resistance of the working oil. Therefore, at a starting time of the vane pump in the low-temperature situation, the pump chambers are not easily defined by the vanes. As described above, in the low-temperature situation, the starting performance of the vane pump is deteriorated.

An object of the present invention is to improve the starting performance of a vane pump.

According to one aspect of the present invention, a vane pump includes a rotor linked to a driving shaft; a plurality of slits formed in the rotor in a radiating pattern to open in an outer circumference of the rotor; a plurality of vanes respectively inserted into the plurality of slits in a slidable manner; a cam ring having an inner circumferential surface on which tip-ends of the vanes slide by rotation of the rotor; pump chambers defined by the rotor, the cam ring, and the pair of adjacent vanes, wherein the plurality of vanes have: a plurality of first vanes formed by applying DLC coating on a base material; and a second vane formed such that the base material is exposed, and the first vanes are respectively inserted into at least two adjacent slits of the plurality of slits.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view of a vane pump according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the vane pump according to the first embodiment of the present invention.

FIG. 3 is a front view of the vane pump according to a second embodiment of the present invention.

FIG. 4 is a front view of the vane pump according to a third embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

First Embodiment

An overall configuration of a vane pump 100 according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

The vane pump 100 is used as a fluid pressure source for a fluid pressure apparatus mounted on a vehicle, such as, for example, a power steering apparatus, a continuously variable transmission, or the like. In this embodiment, the fixed displacement vane pump 100 using working oil as working fluid will be described. The vane pump 100 may also be a variable displacement vane pump.

In the vane pump 100, motive force from an engine (not shown) is transmitted to an end portion of a driving shaft 1, and a rotor 2 linked to the driving shaft 1 is rotated. The rotor 2 is rotated in the clockwise direction in FIG. 1.

As shown in FIGS. 1 and 2, the vane pump 100 includes a plurality of vanes 3 that are provided so as to be able to reciprocate in the radial direction relative to the rotor 2, a cam ring 4 that accommodates the rotor 2 and has a cam face 4a serving as an inner circumferential surface on which tip-ends of the vanes 3 slide by rotation of the rotor 2, a pump body 10 having an accommodating concave portion 10a for accommodating the cam ring 4, and a pump cover 11 that is fastened to the pump body 10 to seal the accommodating concave portion 10a. As shown in FIG. 2, the driving shaft 1 is rotatably supported by the pump body 10.

As shown in FIG. 1, in the rotor 2, slits 7 having openings in an outer circumferential surface of the rotor 2 are formed in a radiating pattern with predetermined gaps. The vanes 3 are respectively inserted into the slits 7 in a reciprocatable manner. In the slits 7, back pressure chambers 8 into which discharge pressure is guided are defined by base-end portions of the vanes 3. In addition, the adjacent back pressure chambers 8 are communicated with each other by a back pressure groove 8a formed in the pump cover 11 (see FIG. 2).

In the vane pump 100, twelve vanes 3 are provided. The vanes 3 are pushed in the directions in which the vanes 3 are drawn out from the slits 7 by the pressure of the working oil guided into the back pressure chambers 8, and tip-end portions of the vanes 3 are brought into contact with the cam face 4a of the cam ring 4. With such a configuration, a plurality of pump chambers 6 are defined in the cam ring 4 by the outer circumferential surface of the rotor 2, the cam face 4a of the cam ring 4, and the adjacent vanes 3. The configuration of the vanes 3 will be described in detail later.

The cam ring 4 is an annular member in which the cam face 4a on the inner circumference has a substantially oval shape. The cam ring 4 has suction regions 4b in which volumes of the pump chambers 6, which are defined between respective vanes 3 that slide on the cam face 4a by the rotation of the rotor 2, are increased and discharge regions 4c in which volumes of the pump chambers 6 are decreased. As described above, respective pump chambers 6 are expanded/contracted by the rotation of the rotor 2. In this embodiment, the cam ring 4 has two suction regions 4b and two discharge regions 4c.

As shown in FIG. 2, the pump cover 11 is arranged so as to be in contact with the one side surface of each of the rotor 2 and the cam ring 4 (upper side surface in FIG. 2), and a side plate 5 is arranged so as to be in contact with the other side surface of each of the rotor 2 and the cam ring 4 (lower side surface in FIG. 2). The pump cover 11 and the side plate 5 are arranged in such a manner that both side surfaces of each of the rotor 2 and the cam ring 4 are sandwiched, and thereby, the pump chambers 6 are sealed.

On an end surface 11a of the pump cover 11 on which the rotor 2 slides, the two arc-shaped suction ports (not shown) are formed so as to respectively open to the two suction regions 4b of the cam ring 4 (see FIG. 1) in a corresponding manner and to guide the working oil to the pump chambers 6. In addition, in the pump cover 11, a suction passage (not shown) through which a tank (not shown) is communicated with the suction ports and that guides the working oil in the tank into the pump chambers 6 through the suction ports is formed.

The side plate 5 has two arc-shaped discharge ports 20 that are formed so as to penetrate through the side plate 5 and open correspondingly to the discharge regions 4c of the cam ring 4.

In the pump body 10, a high-pressure chamber 21 into which the working oil that has been discharged from the pump chambers 6 in the discharge regions 4c is guided is formed. The working oil that has been discharged from the pump chambers 6 is guided the high-pressure chamber 21 through the discharge ports 20 of the side plate 5. The working oil guided into the high-pressure chamber 21 is supplied to an external hydraulic apparatus through a discharge passage (not shown) that is formed in the pump body 10 and is in communication with the high-pressure chamber 21.

In the side plate 5, two arc-shaped back pressure ports 22 that are in communication with the high-pressure chamber 21 are formed. Each of the back pressure ports 22 communicates with the back pressure chambers 8. With such a configuration, the working oil in the high-pressure chamber 21 is guided into the back pressure chambers 8 through the back pressure ports 22.

With the vane pump 100, as the rotor 2 is rotated, the working oil is sucked from the tank to each of the pump chambers 6 in the suction regions 4b of the cam ring 4 through the suction ports and the suction passage, and the working oil is discharged to the outside from each of the pump chambers 6 in the discharge regions 4c of the cam ring 4 through the discharge ports 20 and the discharge passage. As described above, in the vane pump 100, the working oil is supplied/discharged by expansion/contraction of the respective pump chambers 6 caused by the rotation of the rotor 2.

Next, the configurations of the vanes 3 will be specifically described.

As shown in FIG. 1, the plurality of vanes 3 have first vanes 3a that are formed by coating DLC (Diamond Like Carbon) on a base material and second vanes 3b that are formed such that the base material is exposed. A state in which the base material is exposed means a state in which the DLC coating is not applied over the entirety of the vane 3 and the surface of the base material remains exposed as the surface of the vane 3.

The plurality of vanes 3 have two first vanes 3a that are respectively inserted into the slits 7, which are adjacent to each other. Because the first vanes 3a on which the DLC coating is applied have a superior slidability, the viscous resistance of the working oil has less effect on the first vanes 3a. Thus, even in the low-temperature situation in which the viscosity and the viscous resistance of the working oil are high, the first vanes 3a project out from the slits 7 easily by the rotation of the rotor 2. Thereby, one pump chamber (hereinafter referred to as “an initial pump chamber 6a”) is defined by the adjacent first vanes 3a, and the starting performance of the vane pump 100 in the low-temperature situation is improved.

In addition, because the initial pump chamber 6a is defined by the two adjacent first vanes 3a, a part of the working oil discharged from the initial pump chamber 6a is guided into the back pressure chambers 8 through the high-pressure chamber 21 and the back pressure ports 22. Thus, the second vanes 3b on which the DLC coating is not applied are also pushed into the directions in which the second vanes 3b are drawn out from the slits 7 by the pressure in the back pressure chambers 8, and thereby, the second vanes 3b project out from the slits 7 and define the pump chambers 6. As described above, because the initial pump chamber 6a is defined by the two first vanes 3a, it is possible to facilitate projection of other vanes 3 (the second vanes 3b) from the slits 7, and so, it is possible to further improve the starting performance in the low-temperature situation.

Although the first vanes 3a have the superior slidability, because the DLC coating is applied on the base material, the cost required for the manufacture is high. Thus, if all of the plurality of vanes 3 are formed as the first vanes 3a in order to improve the starting performance of the vane pump 100, the manufacturing cost of the vane pump 100 is increased.

In contrast, in the vane pump 100, other ten vanes 3 than the two first vanes 3a are all formed as the second vanes 3b. Even there are only two adjacent first vanes 3a, because the initial pump chamber 6a is defined by the first vanes 3a at the starting time, the working oil discharged from the initial pump chamber 6a is guided into respective back pressure chambers 8, and the projection of the second vanes 3b from the slits 7 is facilitated. Thereby, the starting performance of the vane pump 100 is improved sufficiently. Therefore, by forming only two adjacent vanes 3 of twelve vanes 3 as the first vanes 3a, it is possible to improve the starting performance of the vane pump 100 in the low-temperature situation, and at the same time, it is possible to suppress the increase in the manufacturing cost of the vane pump 100.

In addition, by applying the DLC coating, the wear resistance of the first vanes 3a is also improved. Thus, the durability of the vane pump 100 is also improved.

Next, a modification of the above-mentioned first embodiment will be described.

In the above-mentioned first embodiment, the vane pump 100 has the two suction regions 4b and two discharge regions 4c. Instead of this configuration, the vane pump 100 may have one or at least three suction regions 4b and one or at least three discharge regions 4c.

According to the first embodiment mentioned above, the advantages described below are afforded.

In the vane pump 100, because the sliding resistance of the first vanes 3a on which the DLC coating is applied is small, even in the low-temperature situation, the first vanes 3a project out from the slits 7 easily by the centrifugal force caused by the rotation of the rotor 2. Thus, at the starting time of the vane pump 100, the initial pump chamber 6a is formed easily by the adjacent first vanes 3a. Therefore, it is possible to improve the starting performance of the vane pump 100.

In addition, in the vane pump 100, because the initial pump chamber 6a is defined by the two adjacent first vanes 3a, the working oil is guided into the back pressure chambers 8 through the high-pressure chamber 21 and the back pressure ports 22, and so, the second vanes 3b also project out from the slits 7 and define the pump chambers 6. As described above, because the initial pump chamber 6a is defined by the two first vanes 3a, it is possible to facilitate projection of the second vanes 3b from the slits 7, and so, it is possible to further improve the starting performance in the low-temperature situation.

In addition, in the vane pump 100, even there are only two adjacent first vanes 3a, because the initial pump chamber 6a is defined by the first vanes 3a at the starting time and the working oil is guided into the respective back pressure chambers 8, the projection of the second vanes 3b from the slits 7 is facilitated. Therefore, by forming only two adjacent vanes 3 of twelve vanes 3 as the first vanes 3a, it is possible to improve the starting performance of the vane pump 100 in the low-temperature situation, and at the same time, it is possible to suppress the increase in the manufacturing cost of the vane pump 100.

Second Embodiment

Next, a vane pump 200 according to a second embodiment of the present invention will be described with reference to FIG. 3. In the following, differences from the above-mentioned first embodiment will be mainly described, and components that are the same as those in the vane pump 100 in the above-mentioned first embodiment are assigned the same reference numerals and descriptions thereof will be omitted.

In the above-mentioned first embodiment, the two adjacent first vanes 3a are provided, and all the vanes 3 other than the first vanes 3a are formed as the second vanes 3b. Instead of employing this configuration, the vane pump 200 differs from that in the above-mentioned first embodiment in that three first vanes 3a are provided.

As shown in FIG. 3, the vane pump 200 has three first vanes 3a and nine second vanes 3b.

The three first vanes 3a are arranged side by side in a consecutive manner, and two initial pump chambers 6a are respectively defined between the first vanes 3a.

According to the second embodiment mentioned above, the advantages described below are afforded.

In the vane pump 200, similarly to the vane pump 100, because the sliding resistance of the first vanes 3a on which the DLC coating is applied is small, even in the low-temperature situation, the first vanes 3a project out from the slits 7 easily by the centrifugal force caused by the rotation of the rotor 2. Thus, at the starting time of the vane pump 200, the initial pump chambers 6a are formed easily by the consecutive three first vanes 3a. Therefore, it is possible to improve the starting performance of the vane pump 200.

In addition, in the vane pump 200, similarly to the vane pump 100, because the initial pump chambers 6a are each defined by the two adjacent first vanes 3a, the working oil is guided into the back pressure chambers 8 through the high-pressure chamber 21 and the back pressure ports 22, and thereby, the second vanes 3b also project out from the slits 7 and form the pump chambers. As described above, because two initial pump chambers 6a are defined by the three first vanes 3a, it is possible to facilitate projection of the second vanes 3b from the slits 7, and so, it is possible to further improve the starting performance in the low-temperature situation.

In addition, in the vane pump 200, even at the starting time, the first vanes 3a project out from the slits 7 easily, and the projected first vanes 3a are pushed back into the slits 7 as they enter the discharge regions 4c. By the first vanes 3a that are pushed back into the slits 7, the working oil in the back pressure chambers 8 defined by these first vanes 3a is guided into the back pressure chambers 8 in the adjacent suction regions 4b through the back pressure groove 8a. Thereby, it is possible to further facilitate projection of the vanes 3 in the suction regions 4b.

In addition, in the vane pump 200, because two initial pump chambers 6a are defined, it is possible to increase the flowing amount of the working oil guided into the back pressure chambers 8 at the starting time. Thus, it is possible to allow the second vanes 3b to project out from the slits 7 with high reliability, and it is possible to further improve the starting performance of the vane pump 200.

Third Embodiment

Next, a vane pump 300 according to a third embodiment of the present invention will be described with reference to FIG. 4. In the following, differences from the above-mentioned second embodiment will be mainly described, and components that are the same as those in the vane pump 200 in the above-mentioned second embodiment are assigned the same reference numerals and descriptions thereof will be omitted.

In the above-mentioned second embodiment, two initial pump chambers 6a are defined by the consecutive three first vanes 3a arranged side by side. Instead of employing this configuration, the vane pump 300 differs from that in the above-mentioned second embodiment in that the two initial pump chambers 6a are defined by four first vanes 3a.

As shown in FIG. 4, in the vane pump 300, the vanes 3 have four first vanes 3a and eight second vanes 3b.

In the vane pump 300, the four first vanes 3a are arranged such that pairs of the adjacent first vanes 3a face against each other with the center of the rotor 2 located therebetween. In other words, one initial pump chamber 6a is defined by two adjacent first vanes 3a, and two initial pump chambers 6a that face against each other with the center of the rotor 2 located therebetween are defined by the four first vanes 3a.

According to the above-mentioned third embodiment, in addition to the advantages similar to those offered by the above-mentioned second embodiment, the advantages described below are afforded.

In the vane pump 300, in a case where, in particular, the rotor 2 is provided such that the central axis thereof is inclined from the vertical direction, a state in which a part of the vanes 3 are moved downward in the vertical direction due to the gravitational force and are brought into contact with the cam face 4a (a state in which the vanes 3 are projected out from the slits 7) may be maintained even when the operation is stopped. In the vane pump 300, because the two initial pump chambers 6a that face against each other with the center of the rotor 2 located therebetween are defined, when the operation is stopped, as compared with the case in the vane pumps 100 and 200 according to the first and second embodiments, the first vanes 3a are more likely to be located at the position where a state in which the first vanes 3a are projected out from the slits 7 is achieved (in particular, at the lower portion in the vertical direction). Therefore, in the vane pump 300, even when the operation is stopped, the initial pump chamber 6a is likely to be defined, and it is possible to further improve the starting performance.

The configurations, operations, and effects of the embodiment of the present invention will be collectively described below.

The vane pumps 100, 200, and 300 include: the rotor 2 that is linked to the driving shaft 1; the plurality of slits 7 that are formed in the rotor 2 in a radiating pattern and have opening in the outer circumference of the rotor 2; the plurality of vanes 3 that are respectively inserted into the plurality of slits 7 in a slidable manner; the cam ring 4 that has the cam face 4a on which the tip-ends of the vanes 3 slide by the rotation of the rotor 2; and the pump chambers 6 that are defined by the rotor 2, the cam ring 4, and a pair of adjacent vanes 3. The plurality of vanes 3 have the plurality of first vanes 3a that are formed by applying the DLC coating on the base material and the second vanes 3b that are formed such that the base material is exposed, and the first vanes 3a are respectively inserted into at least two adjacent slits 7 of the plurality of slits 7.

With this configuration, because the sliding resistance of the first vanes 3a on which the DLC coating is applied is small, even in the low-temperature situation, the first vanes 3a project out from the slits 7 easily by the centrifugal force caused by the rotation of the rotor 2. Thus, at the starting time of the vane pumps 100, 200, and 300, the initial pump chamber 6a is formed easily by the adjacent first vanes 3a. Therefore, the starting performance of the vane pumps 100, 200, and 300 is improved.

In addition, the vane pumps 100, 200, and 300 further include the back pressure chambers 8 that are defined in the slits 7 by the base-end portions of the vanes 3 and into which the working oil discharged from the pump chambers 6 is guided.

With this configuration, because the initial pump chamber 6a is defined by the two adjacent first vanes 3a, the working oil is guided into the back pressure chambers 8, and the second vanes 3b also project out from the slits 7 by the pressure of the working oil in the back pressure chambers 8 and define the pump chambers 6. As described above, because the initial pump chamber 6a is defined by the two first vanes 3a, it is possible to facilitate projection of the second vanes 3b from the slits 7, and so, it is possible to further improve the starting performance in the low-temperature situation.

In addition, in the vane pump 100, the plurality of vanes 3 have two first vanes 3a.

With this configuration, even there are only two adjacent first vanes 3a, because the initial pump chamber 6a is defined by the first vanes 3a at the starting time and the working oil is guided into the respective back pressure chambers 8, the projection of the second vanes 3b from the slits 7 is facilitated. Therefore, by forming only two adjacent vanes 3 of the plurality of vanes 3 as the first vanes 3a, it is possible to improve the starting performance of the vane pump 100 in the low-temperature situation, and at the same time, it is possible to suppress the increase in the manufacturing cost of the vane pump 100.

In addition, the vane pump 200 has three first vanes 3a, and the three first vanes 3a are arranged side by side in a consecutive manner.

With this configuration, because two initial pump chambers 6a are defined, at the starting time, it is possible to increase the flowing amount of the working oil guided into the back pressure chambers 8. Thus, it is possible to allow the second vanes 3b to project out from the slits 7 with high reliability, and thereby, it is possible to further improve the starting performance of the vane pumps 200 and 300.

In addition, the vane pump 300 has four first vanes 3a, and the four first vanes 3a are arranged such that the pairs of the adjacent first vanes 3a face against each other with the center of the rotor 2 located therebetween.

With this configuration, because the pairs of the adjacent first vanes 3a are arranged so as to face against each other with the center of the rotor 2 located therebetween, even when the operation of the vane pump 300 is stopped, it is likely that the first vanes 3a are located at the lower portion of the rotor 2 in the vertical direction and the initial pump chamber 6a is defined. Therefore, it is possible to further improve the starting performance of the vane pump 300.

Embodiments of this invention were described above, but the above embodiments are merely examples of applications of this invention, and the technical scope of this invention is not limited to the specific constitutions of the above embodiments.

This application claims priority based on Japanese Patent Application No.2015-191667 filed with the Japan Patent Office on Sep. 29, 2015, the entire contents of which are incorporated into this specification.

Claims

1. A vane pump comprising: a rotor linked to a driving shaft;a plurality of slits formed in the rotor in a radiating pattern to open in an outer circumference of the rotor;a plurality of vanes respectively inserted into the plurality of slits in a slidable manner;a cam ring having an inner circumferential surface on which tip-ends of the vanes slide by rotation of the rotor;pump chambers defined by the rotor, the cam ring, and the pair of adjacent vanes,wherein the plurality of vanes have:a plurality of first vanes formed by applying DLC coating on a base material; anda second vane formed such that the base material is exposed, andthe first vanes are respectively inserted into at least two adjacent slits of the plurality of slits.

2. The vane pump according to claim 1, further comprising back pressure chambers into which working fluid discharged from the pump chamber is guided, the back pressure chambers being defined in the slits by base-end portions of the vanes.

3. The vane pump according to claim 1, wherein the plurality of vanes have the two first vanes.

4. The vane pump according to claim 1, wherein the plurality of vanes have the three first vanes, andthe three first vanes are arranged side by side in a consecutive manner.

5. The vane pump according to claim 1, wherein the plurality of vanes have the four first vanes, andthe four first vanes are arranged such that pairs of the adjacent first vanes face against each other with a center of the rotor located therebetween.